;>,1,0 PERCY SLADEX TEUST EXPEDITION. 



two tiny lateral peaks. Median tentacle missing in all specimens: lateral tentacles 

 arisins^ from a lower level than in L. cornuta, about twice the length of the head, and 

 sparsely ciliate. Palps short and awl-shaped, about the same length as the lateral 

 tentacles. Behind the head is a sliglit nuchal fold with a median peak. 



Elytra (fig. 11) soft and gelatinous, with the margins entire. The inner half is 

 covered with tiny tubei'cles ; but the outer lialf is quite smooth, with fine venations, 

 and situated on the venations is a ring of small eminences parallel to the margin. 

 Some elytra have lost all signs of tubercles. 



Dorsal tuft of setae not long, and directed upwards as in L. cornuta. Setfe (fig. 49) 

 themselves are by no means broad ; but tip is acute, with a rather long, smooth portion 

 between it and spiniferous area. Ventral setiB (fig. 50) are long and conspicuous, with 

 rather short spiniferous area, and a short rather blunt spine under the incurved apex. 



Locality. Zanzibar ; five specimens. The following remarks with regard to condition 

 at capture are from Mr. Crossland's notes : — " Elytra colourless and quite transparent, 

 with a ring of opaque white round jioint of attachment, very easily lost. Body a 

 bright light pink, but this is due to eggs. Really yellowish, with brick-shaped, 

 transverse, light brown markings especially conspicuous posteriorly." 



Genus HALOSYDNA. 



19. Halosydna (1) icilleyi, sp. n. (Plate 21. figs. 44j, 4-5.) 



Measurements. Length 21 mm., breadth with setae 4 mm. ; no. of pairs of elytra 28 ; 

 no. of segments 61. 



Small form, with slightly arched dorsum. Head minvife, round, divided into two 

 by median furrow ; no trace of eyes. Tentacles very short and stumpy, with broad 

 basal joints all arising from head at same level. Median rather longer than lateral 

 tentacles. Palps stout conical structures, equal in length to median tentacle. Elytra 

 occtirring on segments 2, 4, 5, 7, — 23, 26, 29, 32, 33, 35, 37, — entirely covering body, 

 smootli, colourless, very easily detached from elytrophores. Surface not clearly veined, 

 very minute horseshoe-shaped, chitinous tubercles scattered over it. 



Parapodia quite similar to those of M. zeylanica : neuropodium small, with strong 

 aciculum and few fairly short setae (fig. 44), slightly curved, with numerous serrations, 

 ending in a rather acute ape.x. Ventral setae (fig. 45) very similar in shape to those of 

 H. zeylanica, with acute sharply incurved apex ; between the tip and the semilunar 

 cusp a number of short spines, and from the origin of these a parallel series of wavy 

 lines running across the seta. At the side of tiie cusp, in all specimens, a small area 

 occupied by fine parallel striations. 



Locality. Amirante, E 10, 22-85 fathoms. 



In Dr. Willey's account of the collection of Ceylon Polychaeta made by Professor 

 Herdman he describes a worm commensal on echinoderms as Halosydna zeylanica, sp. n. 

 The species found in Mr. Gardiner's collection is undoubtedly nearly related to this 

 It is curious that in both the same anomalous distribution of elytra should occur. 

 The peculiarity is the presence of elytra on successive segments, the thirty-second and 



